fix: confusion group confidence calibration — false positive detection inflation

Issues found through matching program classification analysis:
1. dedup_vs_nodedup: 0.85→0.50 for negative detection (no WS-PREV-KEY
   is not strong evidence for '含まず')
2. validation_vs_keybreak: 0.80→0.55 for has_counter (counter is a
   generic pattern, not specific to key-break)
3. simple_vs_two_stage: 0.80→0.50 for non-open-close-open pattern
   (sequential OPEN is the default for most programs)

Result: matching programs now correctly classified:
- MT01-03/18/20 → マッチング ✅ (was 項目チェック)
- MT16-17 → 二段階マッチング ✅ (unchanged)
- MT32 → 項目チェック(重複含む) ✅ (correct: has WS-PREV-KEY)
- VL01 → 項目チェック(重複含む) ✅ (correct)
- CSV → CSV合并 ✅ (correct)
Regression: 745 passed (3 test expectation bounds updated)

hina/rule_engine/confusion_groups.py

@@ -69,8 +69,8 @@ def resolve_dedup_vs_nodedup(features: dict) -> dict:
         evidence.append("WS-PREV-KEY 存在 → 含重复")
         return {"resolved_type": "項目チェック(重複含む)", "confidence": 0.90, "evidence": evidence}
     else:
-        evidence.append("未检测到 WS-PREV-KEY → 不含重复")
-        return {"resolved_type": "項目チェック(重複含まず)", "confidence": 0.85, "evidence": evidence}
+        evidence.append("未检测到 WS-PREV-KEY → 可能不含重复（置信度低：缺少 WS-PREV-KEY 不代表一定是项目检查）")
+        return {"resolved_type": "項目チェック(重複含まず)", "confidence": 0.50, "evidence": evidence}
 
 
 def resolve_validation_vs_keybreak(features: dict) -> dict:
@@ -90,8 +90,8 @@ def resolve_validation_vs_keybreak(features: dict) -> dict:
         return {"resolved_type": "編集処理(校验)", "confidence": 0.85, "evidence": evidence}
 
     if has_counter:
-        evidence.append("WS-*CNT 计数器存在 → キーブレイク")
-        return {"resolved_type": "キーブレイク", "confidence": 0.80, "evidence": evidence}
+        evidence.append("WS-*CNT 计数器存在 → 可能キーブレイク（置信度低：计数器是通用模式，非决定性证据）")
+        return {"resolved_type": "キーブレイク", "confidence": 0.55, "evidence": evidence}
 
     evidence.append("既无错误字段也无计数器，无法判定")
     return {"resolved_type": "unknown", "confidence": 0.0, "evidence": evidence}
@@ -134,8 +134,8 @@ def resolve_simple_vs_two_stage(features: dict) -> dict:
         evidence.append("OPEN→CLOSE→再OPEN 模式 → 二级匹配")
         return {"resolved_type": "二段階マッチング", "confidence": 0.90, "evidence": evidence}
     else:
-        evidence.append(f"OPEN 模式为 '{open_pattern}' → 简单匹配")
-        return {"resolved_type": "単純マッチング", "confidence": 0.80, "evidence": evidence}
+        evidence.append(f"OPEN 模式为 '{open_pattern}' → 默认为単純マッチング（非決定的: 无 OPEN-CLOSE-OPEN 模式不代表一定是匹配程序）")
+        return {"resolved_type": "単純マッチング", "confidence": 0.50, "evidence": evidence}
 
 
 def resolve_pure_vs_mixed(features: dict) -> dict: